Ab-initio investigation of physical properties of Mg₃XO₄ (X = Cr, Mn, Fe, Co, Ni) materials

The development of new materials depends heavily on meticulous design and theoretical analysis. Density functional theory (DFT) is widely used for this purpose. In this work, Mg₃XO₄ compounds (X = Cr, Mn, Fe, Co, Ni) were investigated to explore their core properties via DFT-based simulations. A thorough examination was conducted on their structural, elastic, mechanical, thermodynamic, electronic, and dynamical features. The negative formation energies calculated for all compositions indicate their dynamic stability and feasibility for synthesis. Elastic constant values confirm that each material meets Born stability conditions. Several polycrystalline mechanical parameters were also assessed. The findings suggest these compounds tend to be brittle, exhibit notable Vickers hardness, and display magnetic behavior. Anisotropy was observed in mechanical moduli such as Young's modulus, shear modulus, and Poisson's ratio. Band structure results show that Mg₃CrO₄, Mg₃MnO₄, and Mg₃FeO₄ exhibit semi-metallic nature, while Mg₃CoO₄ and Mg₃NiO₄ behave metallically, with spin bands overlapping the Fermi level. Phonon dispersion analysis confirms dynamical stability, as all frequencies are positive. Additionally, thermodynamic parameters including free energy, entropy, heat capacity, Debye temperature, melting point, thermal conductivity, and Grüneisen parameter were calculated to further characterize these materials.